Marked hyperleptinemia after high-fat diet associated with severe glucose intolerance in mice

We asked whether the likelihood for mice of the C57BL/6J strain to develop glucose intolerance when fed a high-fat diet is related to the increase in circulating levels of leptin or free fatty acids (FFA). We therefore administered a high-fat diet (58% fat) or a control diet (11% fat) for 1.5 years. NMRI mice were used as a more glucose-tolerant control group. After a high-fat diet, the area under the glucose curve following an intraperitoneal glucose challenge (1g/kg) increased more markedly in C57BL/6J mice (by 42 +/- 8%) than in NMRI mice (by 21 +/- 3%, P = 0.007). Plasma levels of insulin, leptin and FFA increased in both strains of mice, whereas plasma glucose levels were elevated after the high-fat diet only in C57BL/6J mice. The slope of the relationship between body weight and plasma leptin was higher in C57BL/6J mice than in NMRI mice, suggesting leptin insensitivity. Circulating leptin correlated to circulating insulin in both strains of mice, whereas plasma FFA correlated to plasma insulin in NMRI mice but not in C57BL/6J mice. These correlations remained significant after adjustment for body weight. The results show that elevated leptin and FFA levels evolve after high-fat feeding in mice, in conjunction with evolvement of glucose intolerance and hyperglycemia

Effects of glucagon-like peptide-I on glucose turnover in rats

The influences of glucagon-like peptide-I-(7-36) amide (GLP-I; 15 pmol . kg(-1). min(-1)) on glucose turnover were studied in freely moving Wistar rats. In fed rats, GLP-I reduced plasma glucose (from 7.3 +/- 0.2 to 5.6 +/- 0.3 mmol/l; P = 0.017), increased plasma insulin (from 20 +/- 3 to 89 +/- 11 mU/l; P = 0.002), and reduced plasma glucagon (from 44 +/- 1 to 35 +/- 2 pg/ml; P = 0.009) and glucose appearance rate (R(a); from 3.9 1 0.2 to 1.7 +/- 0.7 mu mol . min(-1). 100 g(-1) after 30 min; P = 0.049) without affecting glucose disappearance rate (R(d)). The glucose clearance rate (MCR) was increased (P = 0.048). In 48-h-fasted rats, GLP-I reduced plasma glucose (from 5.0 +/- 0.2 to 4.4 +/- 0.3 mmol/l; P = 0.035) and increased plasma insulin (from 4 +/- 1 to 25 +/- 10 mU/l; P = 0.042) and plasma glucagon (from 43 +/- 3 to 61 +/- 7 pg/ml; P = 0.046). R(a) and R(d) were not significantly affected, although R(a) was lower than R(d) after 15-30 min (P = 0.005) and MCR was increased (P = 0.049). Thus GLP-I reduces R(a) in fed rats and increases MCR in fed and fasted rats. The reduced R(a) seems mediated by an increased insulin-to-glucagon ratio; the increased glucose clearance seems dependent on insulin and a peripheral effect of GLP-I

Gender difference in the glucagon response to glucopenic stress in mice

A gender difference in the glucagon response to insulin-induced hypoglycemia was previously demonstrated in humans. Whether this reflects a gender difference in autonomic activation or in pancreatic α-cell regulation is not known. We investigated the glucagon, epinephrine, and norepinephrine responses to neuroglycopenic stress induced by 2-deoxy-D-glucose (2-DG) or insulin in female and male mice. 2-DG increased plasma glucagon levels by 559 ± 68% in females versus 281 ± 46% in males (P < 0.01). Plasma levels of epinephrine or norepinephrine after 2-DG administration did not differ between genders. During insulin-induced hypoglycemia, the glucagon response was similarly higher in females (P < 0.001), whereas the plasma catecholamine response was higher in males (P < 0.05). In vivo, the glucagon response to carbachol or clonidine was higher in females (P < 0.05). In isolated islets, the glucagon response to carbachol (100 µM; P = 0.003) but not to clonidine (1 µM) was larger in females. We conclude that in addition to a larger α-cell mass (previously described in female mice), an increased sensitivity of the glucagon-producing α-cell to cholinergic activation contributes to the larger glucagon response to glucopenic stress in female mice

Emotional Memory Moderates the Relationship Between Sigma Activity and Sleep-Related Improvement in Affect

Sleep is essential for regulating mood and affect, and it also consolidates emotional memories. The mechanisms underlying these effects may overlap. Here, we investigated whether the influence of sleep on affect may be moderated by emotional memory consolidation. Young adults viewed 45 negative and 45 neutral pictures before taking an afternoon nap measured with polysomnography. Following the nap period, participants viewed the same pictures intermixed with novel ones and indicated whether they remembered each picture. Affect was measured with the Positive and Negative Affect Schedule (PANAS) at baseline before the initial picture viewing task, immediately following the initial picture viewing task, and following the nap. The ratio of positive to negative affect declined over the task period and recovered over the nap period. When controlling for pre-nap affect, NREM sigma activity significantly predicted post-nap affect. Memory for negative pictures moderated this relationship such that a positive association between sigma activity and affect occurred when memory was low but not when memory was high. These results indicate that emotional memory consolidation influences the relationship between nap physiology and mood

β- and α-Cell Dysfunction in Subjects Developing Impaired Glucose Tolerance: Outcome of a 12-Year Prospective Study in Postmenopausal Caucasian Women

OBJECTIVE— This study assessed insulin and glucagon secretion in relation to insulin sensitivity in Caucasian women who develop impaired glucose tolerance (IGT) versus those who maintain normal glucose tolerance (NGT) over a 12-year period

Introductory programming: a systematic literature review

As computing becomes a mainstream discipline embedded in the school curriculum and acts as an enabler for an increasing range of academic disciplines in higher education, the literature on introductory programming is growing. Although there have been several reviews that focus on specific aspects of introductory programming, there has been no broad overview of the literature exploring recent trends across the breadth of introductory programming. This paper is the report of an ITiCSE working group that conducted a systematic review in order to gain an overview of the introductory programming literature. Partitioning the literature into papers addressing the student, teaching, the curriculum, and assessment, we explore trends, highlight advances in knowledge over the past 15 years, and indicate possible directions for future research

Longitudinal maturation of auditory cortical function during adolescence

Cross-sectional studies have demonstrated that the cortical auditory evoked potential (CAEP) changes substantially in amplitude and latency from childhood to adulthood, suggesting that these aspects of the CAEP continue to mature through adolescence. However, no study to date has longitudinally followed maturation of these CAEP measures through this developmental period. Additionally, no study has examined the trial-to-trial variability of the CAEP during adolescence. Therefore, we longitudinally tracked changes in the latency, amplitude, and variability of the P1, N1, P2, and N2 components of the CAEP in 68 adolescents from age 14 years to age 17 years. Latency decreased for N1 and N2, and did not change for P1 or P2. Amplitude decreased for P1 and N2, increased for N1, and did not change for P2. Variability decreased with age for all CAEP components. These findings provide longitudinal support for the view that the human auditory system continues to mature through adolescence. Continued auditory system maturation through adolescence suggests that CAEP neural generators remain plastic during this age range and potentially amenable to experience-based enhancement or deprivation